1. Field of the Invention
The invention relates to a compound, a fluorine-containing polymer, and a radiation-sensitive resin composition.
2. Discussion of the Background
In the field of microfabrication (e.g., production of integrated circuit devices), lithographic technology that enables microfabrication with a line width of 0.10 μm or less has been desired to achieve a higher degree of integration.
Therefore, use of radiation having a shorter wavelength has been studied in order to implement microfabrication with a line width of 0.10 μm or less. Examples of radiation having a short wavelength include deep ultraviolet rays (e.g., mercury lamp bright line spectrum and excimer laser light), X-rays, electron beams, and the like. In particular, KrF excimer laser light (wavelength: 248 nm) and ArF excimer laser light (wavelength: 193 nm) have attracted attention.
As a resist that is suitable for excimer laser light, various resists (chemically-amplified resists) that utilize a chemical amplification effect due to an acid-dissociable functional group-containing component and a component that generates an acid upon irradiation (exposure) (hereinafter may be referred to as “acid generator”) have been proposed.
For example, a chemically-amplified resist that includes a resin containing a t-butyl ester group of a carboxylic acid or a t-butyl carbonate group of phenol, and an acid generator has been proposed. This resist utilizes a phenomenon in which the t-butyl ester group or the t-butyl carbonate group contained in the resin dissociates due to an acid generated upon exposure to form an acidic group (e.g., carboxyl group or phenolic hydroxyl group), so that the exposed area of the resist film becomes readily soluble in an alkaline developer.
Such a lithographic process will be required to form a finer pattern (e.g., a resist pattern with a line width of about 90 nm). A pattern having a line width of less than 90 nm may be formed by reducing the wavelength of the light source of the exposure system, or increasing the numerical aperture (NA) of the lens.
In recent years, liquid immersion lithography has been proposed as lithographic technology. In liquid immersion lithography, a liquid refractive medium (immersion liquid) (e.g., purified water or fluorine-containing inert liquid) is interposed (at least over the resist film) between the lens and the resist film formed on the substrate during exposure.
According to liquid immersion lithography, the optical space (path) is filled with a liquid (e.g., pure water) having a high refractive index (n) instead of an inert gas (e.g., air or nitrogen) so that the resolution can be increased without causing a decrease in depth of focus in the same manner as in the case of using a short-wavelength light source or a high NA lens. A resist pattern that exhibits excellent resolution and an excellent depth of focus can be inexpensively formed by liquid immersion lithography using a lens provided in an existing system. A polymer, an additive, and the like for forming a resist used for liquid immersion lithography have been proposed (see WO04/068242, Japanese Patent Application Publication (KOKAI) No. 2005-173474 and Japanese Patent Application Publication (KOKAI) No. 2006-48029, for example).